1. Field of the Invention
The present invention relates to an apparatus for automatically conveying cartridges to a magnetic tape unit which records and reproduces data by using a magnetic cartridge tape (hereinafter simply referred to as "cartridge") as a recording medium.
2. Description of the Related Art
In recent years, automatic operation of magnetic tape units has become so advanced that it is necessary to employ an apparatus for automatically conveying cartridges to take a cartridge that is to be processed from a rack of a cell mechanism, in which a plurality of cartridges are stored, and to convey the cartridge to a magnetic tape apparatus.
In the apparatus for automatically conveying cartridges, a robot that requires a servo control operation has generally been controlled by firmware. Furthermore, the torque required from a motor to drive the apparatus for automatically conveying cartridges varies depending upon the apparatuses due to mechanical tolerance, the environment in which the apparatus for automatically conveying cartridges is used and the time of use. It is presumed that these differences result from a change in friction and mechanical tolerance.
Despite the occurrence of the above-mentioned situations, any magnetic tape apparatus can be easily coped with if mechanical tolerance in the apparatus is absorbed by the firmware that controls the apparatus for automatically conveying cartridges. Moreover, incorporating a mechanical unit in the apparatus for automatically conveying cartridges maintaining precision requires laborious work as well as considerable expense. It therefore becomes necessary to assemble the apparatus while maintaining precision to a certain degree and, then, control the operation is corrected by the firmware.
As the apparatus is designed to operate automatically, furthermore, it is required to operate unattended. Therefore, it is necessary to develop a library unit which stores a number of cartridges and conveys a cartridge to the magnetic tape apparatus to automatically execute recording/reproducing operation. Even when the apparatus for automatically conveying cartridges is coupled to a library unit to automatically convey the cartridges, however, it is not possible to automatically convey the cartridges when there are included cartridges from which the leader block has been pulled out or when the detector mechanisms have been broken in the apparatus for automatically conveying the cartridges. In such a case, the operation must be carried out by an operator.
Even in an apparatus in which the detector mechanisms have been broken, therefore, the processing can be continued if the cartridge contained therein can be taken out. It therefore becomes necessary to automatically continue the processing without assistance from an operator or maintenance personnel. This is related to enhancing the retry control operation when an error has occurred. When the operator uses the apparatus for automatically conveying cartridges, furthermore, the apparatus must be easily operated. For this purpose, the operation performance must be enhanced. Therefore, the operation must be simple and easy.
The prior art will now be described with reference to the drawings.
.sctn.1: Description of a Cartridge and Apparatus for Automatically Conveying Cartridges--See FIGS. 1A to 1D
FIG. 1A is a perspective view of a cartridge, FIG. 1B is a side view of a conventional ACL apparatus for a single unit, FIG. 1C is a side view of a conventional ACL apparatus for attachment to a library unit, and FIG. 1D is a plan view of a conventional accessor. In the following description, the apparatus for automatically conveying cartridges is referred to as an ACL (automatic cartridge loading) apparatus, the magnetic tape unit is referred to as "MTU", and the magnetic cartridge tape is referred to as "cartridge".
As a magnetic tape recording medium, there has heretofore been known a cartridge (magnetic cartridge tape) 1 that is shown (3480-type magnetic cartridge tape). There has been known an ACL apparatus for automatically conveying cartridges to the MTU which records and reproduces the data by using the cartridge 1. The ACL apparatus may be either an ACL apparatus 4 for a single unit or an ACL apparatus 5 for attachment to a library unit.
The ACL apparatus 4 for a single unit is used in combination with the MTU (as a unitary structure) and automatically conveys the cartridge to the MTU 6. The ACL apparatus 5 for attachment to a library is used in combination with the MTU 6 (as a unitary structure) and is further mechanically coupled to a library unit 12.
In this case, the library unit 12 is equipped with a cell (rack mechanism) for storing a number of cartridges therein, an MTU (unit separate from the MTU 6 combined with the ACL unit), an accessor mechanism for automatically conveying cartridges to the cell and to the MTU, and a cartridge access station (CAS) for automatically loading/discharging the cartridges.
As shown, the ACL apparatus 4 for a single unit is used in combination with the MTU 6 (as a unitary structure). The ACL apparatus 4 for a single unit is equipped with a cell mechanism 10 having many racks (cells) 11 for holding cartridges, and an accessor mechanism for automatically conveying cartridges. The accessor mechanism is provided with an accessor (mechanism which grips a cartridge and moves) 8, a shaft 9 and an accessor drive mechanism which includes a motor.
The accessor 8 is driven by the accessor drive mechanism and ascends or descends along the shaft 9 but does not turn on a horizontal plane. The cartridge can be inserted in each rack 11 of the cell mechanism 10, by hand, from the external side. The accessor 8 grips the cartridge inserted in the rack 11 of the cell mechanism 10, conveys it and loads it into the MTU 6. The cartridge loaded into the MTU is subjected to read/write processing. The cartridge processed in the MTU 6 is gripped by the accessor 8, conveyed to the cell mechanism 10 and is discharged into the rack 11.
Like the ACL apparatus 4 for a single unit, the ACL apparatus 5 for attachment to a library unit is used in combination with the MTU 6 and is further coupled (mechanically coupled) to a library unit 12. In this case, the ACL apparatus 5 for attachment to a library unit is provided with the accessor mechanism and the cell mechanism 10. Here, the cell mechanism 10 is provided with an entry cell 13 and an exit cell 14.
The ACL apparatus 5 for attachment to a library unit automatically exchanges the cartridge with the library unit 12 through the entry cell 13 and the exit cell 14. For instance, a cartridge stored in the library unit 12 is conveyed by the ACL apparatus 5 for attachment to a library unit to the MTU 6 (which is separate from the MTU in the library unit 12) and is subjected to read/write processing.
The accessor 8 is provided with catcher hands 19 (located on both sides) which open and close by turning about a rotary center shaft 20 to grip or release the cartridge 1, a catcher motor 21 for driving the catcher hands 19, feed motors 23 for feeding/returning (pulling/discharging) the cartridge by driving the feeder belts, a presence-of-cartridge sensor 25 for detecting the presence of a cartridge on the rack of the cell mechanism 10, a first cell side sensor 38 and a second cell side sensor 39 for detecting the presence of a cartridge in the accessor 8. The catcher hands 19 are disposed on the side of the cell mechanism 10.
.sctn.2: Controlling the Portions of the ACL Apparatus
Described below are the operations for controlling the portions of the ACL apparatus 4 for a single unit and of the ACL apparatus 5 for attachment to a library unit. In the following description, both the ACL apparatus 4 for a single unit and the ACL apparatus 5 for attachment to a library unit are simply referred to as "ACL apparatuses". Furthermore, the racks of the cell mechanism provided for the ACL apparatus 4 for a single unit and the entry cell and exit cell of the cell mechanism provided for the ACL apparatus 5 for attachment to a library unit are all referred to as "racks" or "cells".
(1) Controlling the Accessor 8
The accessor 8 in a conventional ACL apparatus is provided with catcher hands 19 which are closed or opened to grip or release the cartridge 1. For instance, when a cartridge held in the rack 11 of the cell mechanism 10 is to be pulled (fed) into the accessor, the catcher hands 19 are opened and are positioned to the cell mechanism 10. The catcher hands 19 are then closed to grip the cartridge and are pulled (fed) into the accessor 8.
When the cartridge in the accessor 8 is to be loaded into the MTU 6, the accessor 8 holding the cartridge is positioned to the MTU 6 (positioned in the direction of height) and the cartridge is loaded into the MTU 6.
(2) Detecting a Cartridge Present in the Cell Mechanism 10
The cartridge 1 present on the rack of the cell mechanism 10 has heretofore been detected by the presence-of-cartridge sensor 25 provided on the accessor 8 in a manner as described below.
1 The cartridge 1 present on the rack (cell) has simply been detected by the presence-of-cartridge sensor 25, without making sure if the presence-of-cartridge sensor 25 itself is functioning properly or not.
2 Whether the presence-of-cartridge sensor 25 works properly or not is confirmed by the initialization processing only at the time when the power source circuit is closed.
(3) Controlling the position of the rack (cell).
So far, the position of the rack of the cell mechanism 10 has been corrected as described below.
1 The presence-of-cartridge sensor 25 is furnished with a function for detecting the position of the rack (cell), and mechanical dispersion due to mounting of the rack or due to the rack (cell) itself is absorbed by the presence-of-cartridge sensor 25.
2 The apparatus not equipped with the presence-of-cartridge sensor 25 could not absorb dispersion of the racks (cells).
3 In assembling the cell mechanism 10 of the ACL apparatus 5 for attachment to a library unit, positioning must be accomplished relative to the library unit and, hence, the cell mechanism 10 has been so assembled as to suppress dispersion of the racks (cells) without, however, correcting the positions of the racks (cells) in a subsequent step.
(4) Pushing the Leader Block into the Cartridge
When the leader block 2 of the cartridge 1 has been pulled out, the ACL apparatus 4 for a single unit informs the operator of the fact that the leader block 2 has been pulled out, informs an error and discharges the cartridge 1. Even the ACL apparatus 5 for attachment to a library unit discharges the cartridge 1 without pushing in the leader block 2. Therefore, the cartridge 1 from which the leader block 2 has been pulled out is discharged without being processed.
(5) Controlling the Feeder Belts
So far, when a cartridge gripped by the catcher hands 19 is to be discharged (returned) to the cell mechanism 10 or to the MTU 6 by the accessor 8, the motive power of the feeder motors 23 is transmitted to the feeder belts to discharge the cartridge. When there is no cartridge in the accessor 8, the feeder motors 23 are not driven and the feeder belts remain at rest. Therefore, the feeder belts are driven at one place only.
(6) Controlling the Feeder Learning
The accessor 8 has been equipped with a feeder mechanism comprising feeder motors 23 and feeder belts in order to discharge (return) the cartridge in the accessor 8 into the cell mechanism 10 or into the MTU 6 or to pull (feed) the cartridge in the cell mechanism 10 or in the MTU 6 into the accessor 8. However, the feeder mechanism of the accessor 8 does not have a learning function but simply feeds or returns the cartridge.
(7) Initializing the Cartridge
The cartridge present in the accessor 8 is detected by using the first cell side sensor 38 and the second cell side sensor 39. When the power source circuit is closed or an error has occurred, however, the accessor 8 is not initialized.
(8) Retrying the Feeder Mechanism
The accessor 8 is equipped with a feeder mechanism comprising feeder motors 23 and feeder belts in order to discharge (return) the cartridge in the accessor 8 into the cell mechanism 10 or into the MTU 6, or to pull (feed) the cartridge in the cell mechanism 10 or in the MTU 6 into the accessor 8. When an error occurs due to the operation for feeding or returning the cartridge, the accessor 8 is positioned again to the cell mechanism 10 or to the MTU 6, and the feeder mechanism is operated again.
(9) Returning the Cartridge
When the cartridge in the accessor 8 is to be discharged (returned) onto the rack of the cell mechanism 10, the accessor 8 is not equipped with a detection mechanism for detecting the returning state; i.e., the accessor 8 is moved in the discharging direction by a predetermined amount to discharge the cartridge after the cartridge is no longer detected by the first cell side sensor 38 and the second cell side sensor 39 that detects the cartridge properly held in the accessor 8. That is, when the cartridge is to be returned, the conventional apparatus does not detect to which position the cartridge is discharged but simply discharges the cartridge onto the rack so as to overrun to some extent.
(10) Controlling the Position of Cartridge (Controlling the Overrunning of Cartridge)
The cartridge in the accessor 8 is discharged (returned) onto the rack of the cell mechanism 10 so as to overrun to some extent (discharged to go a little ahead of the specified holding position). That is, when the cartridge is discharged by the conventional apparatus, the cartridge is not controlled for its flying (overrunning) but is simply discharged onto the rack.
(11) Discriminating Between New and Old Devices
The conventional apparatus has not been equipped with a function for automatically discriminating a new ACL apparatus or an old ACL apparatus. The type of the apparatus has been discriminated by employing both new and old firmware or by setting in the apparatus data related to the types of the apparatuses.
The above-mentioned conventional apparatus involves the problems as described below.
(1) Controlling the Catcher Hands of the Accessor
The catcher hands 19 have been driven to be either opened or closed (open or closed state is based on the side of the cell mechanism 10) but not to assume an intermediate position. In the ACL apparatus 4 for a single unit, therefore, when the cartridge is loaded into the MTU 6, for example, the catcher hands 19 are opened on the side of the MTU 6 but are closed on the side of the cell mechanism. When the operator attempts to pull the cartridge on the rack of the cell mechanism 10 at a height same as the MTU 6 or attempts to insert the cartridge into the rack, therefore, the catcher hands 19 which are closed on the side of the cell mechanism 10 enter into the rack and become an obstacle.
In the ACL apparatus 5 for attachment to a library unit, furthermore, when the rack at the position of the MTU 6 (rack at the same height as the MTU 6) is used as the entry cell 13, the MTU 6 becomes flush with the entry cell 13, and the accessor 8 does not need to ascend or descend. Therefore, the shortest time is required for loading the cartridge into the MTU 6, but the accessor 8 becomes an obstacle; i.e., the accessor in the library unit is not allowed to freely access the entry cell 13. Therefore, the entry cell 13 has been deviated from the position (height) of the MTU 6. Accordingly, an extended period of time is required for loading the cartridge into the MTU 6.
(2) Detecting the Presence of a Cartridge on the Rack
1 In the case of the ACL apparatus 5 for attachment to a library unit, whether there is a cartridge in the entry cell 13 or in the exit cell 14 is detected by the presence-of-cartridge sensor 25. During the ordinary operation, however, whether the presence-of-cartridge sensor 25 itself is normally working or not has not been checked.
When the cartridge in the MTU 6 is to be discharged into the exit cell 14, first, the presence-of-cartridge sensor 25 determines whether there is a cartridge or not. Only when it is so judged that there is no cartridge, is the cartridge in the MTU 6 conveyed by the accessor 8 and discharged into the exit cell 14.
When it is so judged that there is a cartridge in the exit cell 14, however, it is not allowed to discharge the cartridge in the MTU 6 into the exit cell 14. In such a case, it is not judged whether the cartridge really exists in the exit cell 14 or the presence-of-cartridge sensor 25 is erroneously detecting a cartridge, but an error is informed to the host unit.
When it is so judged that there is a cartridge though there really is no cartridge in the exit cell 14, the software which control the library unit 12 assumes that a cartridge exist in the exit cell 14 when it does not and control of cartridge is difficult.
2 During an ordinary operation, whether or not the presence-of-cartridge sensor 25 is properly functioning has not been checked. Therefore, if the presence-of-cartridge sensor 25 has been broken, a cartridge in the exit cell 14 may not be detected by the presence-of-cartridge sensor 25. As a result, it is often judged that there is no cartridge despite there really being a cartridge in the exit cell 14.
In such a case, the accessor in the library unit 12 could not access the exit cell 14 since it was judged by the ACL apparatus 5 for attachment to a library unit that there is no cartridge in the exit cell 14. Therefore, when it is desired to convey the cartridge to another MTU in the library unit 12, the operator must take out the cartridge from the exit cell in the ACL apparatus 5 for attachment to a library unit and must insert it again into the library unit 12 requiring an increased amount of operation.
3 When the cartridge is held in a tilted manner in the entry cell 13 or in the exit cell 14, the presence of the cartridge is not correctly detected, and it is often regarded that no cartridge is present even though there really is a cartridge present. This makes it difficult to determine the number of the cartridges by the software that manages the library unit 12.
(3) Correcting the Position of the Rack (Cell) of the Cell Mechanism
Correcting the position of the rack (cell) is as described below.
1 When the accessor 8 has accessed the rack (cell) of the cell mechanism 10 without correcting the position of the rack of the cell mechanism 10, the accessor 8 is often positioned deviated from the rack and the cartridge is often not pulled into the accessor 8 from the rack.
2 In the above-mentioned case 1, the cartridge can be pulled into the accessor 8 upon retrying. However, an extended access time is required since the retrying is effected each time.
3 When the rack and the accessor 8 are deviated from each other, the cartridge is not taken out from the rack or the cartridge is not returned back to the rack, resulting in an error.
(4) Pushing the Leader Block
The leader block of the cartridge is pushed as described below.
1 The cartridge from which the leader block has been pulled out cannot be loaded into the MTU 6 and is, therefore, discharged without subjecting it to the read/write processing. In the ACL apparatus 4 for a single unit, in this case, this fact is reported to the operator to have the leader block pushed in to continue the processing. When such an event occurs in the batch job during the night, however, the processing must be interrupted.
2 In the ACL apparatus 5 for attachment to a library unit, even when the operator is informed of the fact that the leader block has been pulled out, the cartridge is taken out from the library unit 12 and is processed. Therefore, the processing is interrupted during this period often resulting in a tremendous amount of damage.
3 In the case of the ACL apparatus 4 for a single unit, the cartridge discharged onto the rack (cell) of the cell mechanism 10 is taken out by hand by the operator from the rack (cell) and is stored. Therefore, there arises no problem even if the leader block has been pulled out at the time when the cartridge is discharged.
In the ACL apparatus 5 for attachment to a library unit, however, the next processing is automatically carried out without being assisted by the operator. When the leader block has been pulled out, therefore, there arises a problem in that the cartridge cannot be loaded into the library unit 12 when the cartridge is taken out from the exit cell 14 in the ACL apparatus 5 for attachment to a library unit and is loaded into the MTU (MTU in the library unit 12) which is not prepared to cope with the cartridges into which the leader block has not been pushed.
(5) Driving the Feeder Belts
The cartridge is conveyed from the rack of the cell mechanism 10 to the accessor 8, from the accessor 8 to the MTU 6, and is returned from the MTU 6 back to the accessor 8. Therefore, the feeder belts provided in the accessor 8 are driven at the same portions at all times. Moreover, the control operation for pushing the leader block so works as to push the leader block and then pulls the cartridge into the accessor 8. In this case, too, therefore, the control operation is executed at the same positions at all times. Therefore, the feeder belts slip at the same portions only and are conspicuously worn out at these portions but are not worn out at other portions.
(6) Controlling the Feeder Learning
The learning control has not been effected for the feeder mechanism in the conventional accessor 8. Therefore, the speed of the feeder motors 23 of the accessor 8 varies, friction varies depending upon the cartridges, and the amount of overrunning often increases when the cartridge is pulled into the accessor 8 from the rack of the cell mechanism 10.
In this case, when the feeder motors 23 are stopped after the cartridge is detected by the second cell side sensor 39, the cartridge overruns up to a position where it is not detected by the second cell side sensor 39. Therefore, the cartridge must be once properly returned back into the accessor 8. When the cartridge is discharged from the accessor 8 into the rack of the cell mechanism 10, furthermore, the cartridge overruns in varying amounts. Therefore, overrunning of a predetermined amount is not accomplished.
(7) Initializing the Cartridge
So far, the accessor 8 has not been initialized when the power source circuit is closed or when an error has occurred. When the power source circuit is closed or when an error has occurred, therefore, it appears that there is no cartridge though a cartridge really exists in the accessor 8. Therefore, the accessor 8 ascends or descends in a state where the cartridge has been missed or the cartridge has not been properly held in the accessor 8, causing the cartridge to be broken or the apparatus to be damaged.
(8) Retrying the Feeder Mechanism
So far, the cartridge has been fed or returned by the feeder mechanism in the accessor 8. When an error occurs in the feeding/returning operation of the cartridge, the accessor 8 is positioned to the cell mechanism 10 or to the MTU 6, and is tried again.
When the feeder mechanism is retried, however, the accessor 8 is located at the same position at all times, i.e., located at a position where the rack should exist even though the rack in practice might have deviated (the rack position is not corrected). When the rack position is deviated, therefore, the accessor 8 cannot be properly positioned to the deviated rack. Despite the feeder mechanism being retried, therefore, the cartridge is neither fed nor returned, and an error occurs.
(9) In the conventional apparatus, the cartridge that is to be returned is simply discharged onto the rack to overrun to some extent without detecting where the cartridge is discharged. In the conventional control operation, therefore, there is no guarantee that the cartridge has returned back to the rack, and there remains a possibility that the cartridge is erroneously recognized to have returned back to the rack though it has not really returned back to the rack due to some obstacle like damage to the motor.
(10) Controlling the Position of Cartridge (Controlling the Overrunning)
When the cartridge is to be discharged (returned) in the conventional apparatus, the cartridge is not controlled for its position (overrunning) but is simply discharged onto the rack. In this case, the state of the cartridge (processed/unprocessed state) is displayed on the operator panel but without looking at the operator panel, the operator could not judge whether the cartridge on the rack is the one that has not been processed or not. There remains a problem in that if the LED of the operator panel breaks, it becomes difficult to determine whether the cartridge is the one that has not been processed or not.
(11) Discriminating Between New and Old Devices
As an ACL apparatus of the improved version is placed in the market as a new type of ACL apparatus, it becomes necessary to detecting the type of the ACL apparatus. So far, this could be coped with by setting data related to the type of the apparatus (data related to the new and old types) in the ACL apparatus or by employing two types of firmware in the new apparatus and in the old apparatus, respectively. When the data related to the types of the apparatuses are to be set, however, the operation involves mistakes, and the operator must set the data again requiring a cumbersome operation.
Furthermore, when the two firmwares are employed, i.e., when the respective firmwares are input to different apparatuses, it becomes impossible to operate the system and mistakes are inevitably involved in the operation.